1. Field of the Invention
The present invention relates to drainage of fluids from body cavities and, more particularly, to an apparatus for use in draining fluids from the chest cavity.
2. The Prior Art
The thoracic or chest cavity is a closed structure essentially formed by the thoracic skeleton and muscles. The interior of the thoracic cavity is partitioned by the mediastinum, which consists of connective tissue which surrounds and holds together the esophagus, trachea, heart, aorta and other major vessels. The mediastinum divides the interior of the thoracic cavity into lung chambers (called pleural cavities), each of which contains one of the lungs.
The lungs are composed of elastic fibers which expand and contract during the normal breathing process. Expansion of the lung occurs during inhalation. When a person inhales, the diaphragm, which is mostly muscle, contracts and pulls downward. At the same time the chest muscles pull the chest wall up and out, with the result that the two chambers inside the thoracic cavity are expanded. The expansion of the two chambers in the thoracic cavity creates a negative pressure which exerts a pull on the lungs causing the lungs to expand and thereby allowing air to be drawn into the lungs. Similarly, during exhalation the rib cage and diaphragm contract, reducing the negative pressure in the two chambers which reduces the force on the lungs allowing them to contract so that sir is exhaled.
When the chest wall is penetrated, either by surgical intervention or accidentally, air is permitted to enter the pleural cavity. As air enters negative pressure is no longer exerted on the lung, which results in pneumothorax, a condition in which the elastic fibers of the lung recoil or collapse. If air continues to leak into the pleural cavity a condition known as tension pneumothorax may develop. In this condition the pressure within the pleural cavity rises to the point where it causes the mediastinum, including the heart and the other major vessels supported in the mediastinum, to be pushed towards the unaffected lung. Should the pressure become great enough it can collapse the unaffected lung and interfere with heart actinon and can thus lead to death within a few minutes.
In order to restore normal breathing following pneumothorax, the air and other fluids which have entered the pleural cavity must be removed from around the lung. This is typically accomplished by inserting one or more chest catheters into the pleural cavity and then connecting the catheters to a drainage system which is used to collect the fluids drained from the pleural cavity.
There are several types of prior art drainage systems which have been used for this purpose. For example, one type of system utilizes gravity to effect drainage of the fluids from the pleural cavity. In this type of system, a bottle is placed below the level of the patient's chest. The bottle is closed at its top by a rubber stopper through which a drainage tube is inserted. The drainage tube is attached at one end to the catheter inserted into the patient's chest. The other end of the drainage tube extends through the stopper to a point near the bottom of the bottle. A sterile liquid such as saline solution is used to fill the bottle to a point which covers the end of the drainage tube. The sterile liquid is intended to act as a seal or one-way check valve which prevents air from moving back up through the drainage tube to the patient's chest. The bottle is also vented to atmosphere through the rubber stopper so that when the bottle is placed below the level of the patient's chest, gravity will effect drainage of fluid from the pleural cavity into the drainage bottle.
This system will not work if the lung is fully collapsed, and it has the further disadvantage that it is difficult to overcome air leaks around the catheter. Moreover, at times there may be a major fluid leak which requires additional drainage capacity. Thus, suction drainage systems have also been used in the prior art to obtain increased drainage capacity. Suction drainage systems typically include a water manometer which is connected to a source of suction and which controls the level of suction applied to the pleural cavity of the patient, since an uncontrolled level of suction may damage the surrounding tissue. The manometer bottle is in turn connected to a bottle which contains a water seal similar to the type of water seal used in a gravity drainage system. The bottle containing the water seal may then be also connected to a third bottle which is used as the drainage bottle for collecting the fluids that are drained from the patient's chest cavity.
One of the disadvantages experienced with the use of this type of three bottle suction drainage system is the rather complicated procedure for setting up the system and interconnecting the three bottles. Also, the system is somewhat inconvenient to use because the bottles must be rinsed, washed and sterilized before they can be used again on other patients.
A more recent system which overcomes some of the disadvantages of the three bottle suction drainage system is illustrated and described in U.S. Pat. Nos. 3,363,626 and 3,363,627. These patents describe a unitary or consolidated "three bottle" apparatus which is constructed of plastic and which is disposable. Rather than using separate bottles, the apparatus replaces the bottles with separate chambers that are formed as part of a single container. The apparatus retains the basic concept of the three bottle suction drainage system because one of the chambers of the apparatus is used as a manometer, and is connected to a second chamber which is used as a water seal. The second chamber is connected to a third chamber which is used as the drainage chamber for receiving fluids drained from the patient's chest cavity.
While the apparatus described in these patents simplifies the set up procedure of the basic three bottle suction drainage system and provides for convenient disposal of the system after each use, this apparatus is relatively complicated in its structure and is expensive to manufacture and use. Moreover, like the gravity drainage system and the three bottle suction drainage system, the apparatus of these patents continues to rely upon the use of an underwater seal which is intended to prevent fluids from re-entering the patient's pleural cavity. However, in practice, an underwater seal does not always prevent fluids from re-entering the patient's chest cavity. For example, if the patient's bronchial tubes are blocked the patient must take deeper breaths in order to expand the lungs to permit air flow around this blockage. When the patient gasps for air or continually takes these kinds of deep breaths, a sufficiently high negative pressure may be developed in the pleural cavity that the liquid used to provide the water seal may be sucked back through the tube and catheter and into the pleural cavity. This obviously increases the risk of contamination to the patient, as well as hampering recovery of the patient's normal respiration.
Thus, what is needed in the art is a suction drainage system which is less expensive and can be economically disposed of after each use and which also overcomes the disadvantages of the prior art type of systems which require the use of an underwater seal, with its attendant disadvantages. Such an invention is described and claimed herein.